SSHSecure/sshkeys/ed25519.go

/*
   SSHSecure - a program to harden OpenSSH from defaults
   Copyright (C) 2020  Brent Saner

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

package sshkeys

import (
	"crypto/ed25519"
)

func (k *SSHPrivKey) generateEd25519() error {
	if k.Key != nil || k.PublicKey.Key != nil {
		return nil // Just no-op; already generated.
	}
	// We cast "pk" (public key) to _ because it's an interface{} that we can't seem to
	// assert to []byte. I've tried iterating, a type assertion, initializing,... nada.
	// Luckily it's at a fixed half of the secret key.
	if _, s, err := ed25519.GenerateKey(nil); err != nil {
		return err
	} else {
		k.Key = s
		ks := len(s) - ed25519.PublicKeySize
		k.PublicKey.Key = s[ks:]
		k.BitSize = ed25519Len
		k.PublicKey.KeyType = KeyEd25519
	}
	return nil
}